Blind signature allows the sender to blind the message first, then the signer signs the blind message, and finally the message owner removes the blind factor in the signature to get the signer's signature on the original message. Blind signature is a special digital signature technology adopted by the receiver, which does not allow the signer to obtain the specific content of the signed message. In addition to the general digital signature conditions, the following two attributes must be met:

1. The signer is invisible to the message he signed, that is, the signer does not know the specific content of the message he signed.

2. The signature message is untraceable, that is, when the signature message is made public, the signer cannot know when he signed it.

Regarding blind signature, a very intuitive explanation is given: the so-called blind signature is to put the hidden file into the envelope first, and the process of removing the blind factor is to open the envelope. No one can read the document when it is in the envelope. Signing a document means putting carbon paper in an envelope. When the signer signs the envelope, his signature will be signed on the document through carbon paper.

Generally speaking, a good blind signature should have the following properties:

1. unforgettable. No one can generate a valid blind signature in his own name except the signer himself. This is a basic attribute.

2. It is undeniable. Once the signer signs the message, he can't deny his signature.

3. blindness. Although the signer signed the message, it is impossible for him to get the specific content of the message.

4. untraceability. Once the signature of a message is made public, the signer cannot be sure when he signed it.

Blind signatures satisfying the above properties are considered to be secure. These four properties are not only the standards we should follow in designing blind signatures, but also the basis for judging the performance of blind signatures.

In addition, the operability and efficiency of the scheme are also very important when designing blind signatures.

Factors. The operability and implementation speed of blind signature depend on the following aspects:

1. The length of the key;

2. The length of blind signature;

3. Algorithm and verification algorithm of blind signature.